From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6356AC43465 for ; Mon, 21 Sep 2020 15:19:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A23920756 for ; Mon, 21 Sep 2020 15:19:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IOBjkXZU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727593AbgIUPT2 (ORCPT ); Mon, 21 Sep 2020 11:19:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:42671 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727171AbgIUPT1 (ORCPT ); Mon, 21 Sep 2020 11:19:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600701566; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=78VYwFftorgadheBNYzJKmL144uRfgx6TOEZIwj+BGo=; b=IOBjkXZUjYSh8HDHu/5BsAS16smU/N9pOZaioK7T3L0PlzKSf1aC4OEAqHEc9Y2Ikj3kaX O091zFNLigHTj009mk9OzF38hjcbjv9AkvcS0wH4Ha9jFgJIHomO4uL5Yh4V73IKWjmzZ+ 2Px45NgrlOiQ5M0Qgar2eWzWhVpCymc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-535-gNN5vVhCM7KoxqTm9vt0JQ-1; Mon, 21 Sep 2020 11:19:18 -0400 X-MC-Unique: gNN5vVhCM7KoxqTm9vt0JQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 567BE801AE2; Mon, 21 Sep 2020 15:19:16 +0000 (UTC) Received: from treble (ovpn-119-131.rdu2.redhat.com [10.10.119.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id ECE9655778; Mon, 21 Sep 2020 15:19:14 +0000 (UTC) Date: Mon, 21 Sep 2020 10:19:13 -0500 From: Josh Poimboeuf To: Ilie Halip Cc: linux-kernel@vger.kernel.org, Nick Desaulniers , Rong Chen , Marco Elver , Philip Li , Borislav Petkov , kasan-dev@googlegroups.com, x86@kernel.org, clang-built-linux@googlegroups.com, kbuild test robot , Peter Zijlstra , Nathan Chancellor Subject: Re: [PATCH v2] objtool: ignore unreachable trap after call to noreturn functions Message-ID: <20200921151913.rrfbqfnrhfmb26w4@treble> References: <20200918154840.h3xbspb5jq7zw755@treble> <20200919064118.1899325-1-ilie.halip@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200919064118.1899325-1-ilie.halip@gmail.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 19, 2020 at 09:41:18AM +0300, Ilie Halip wrote: > With CONFIG_UBSAN_TRAP enabled, the compiler may insert a trap instruction > after a call to a noreturn function. In this case, objtool warns that the > ud2 instruction is unreachable. > > This is a behavior seen with clang, from the oldest version capable of > building the mainline x64_64 kernel (9.0), to the latest experimental > version (12.0). > > objtool silences similar warnings (trap after dead end instructions), so > so expand that check to include dead end functions. > > Cc: Nick Desaulniers > Cc: Rong Chen > Cc: Marco Elver > Cc: Philip Li > Cc: Borislav Petkov > Cc: kasan-dev@googlegroups.com > Cc: x86@kernel.org > Cc: clang-built-linux@googlegroups.com > BugLink: https://github.com/ClangBuiltLinux/linux/issues/1148 > Link: https://lore.kernel.org/lkml/CAKwvOdmptEpi8fiOyWUo=AiZJiX+Z+VHJOM2buLPrWsMTwLnyw@mail.gmail.com > Suggested-by: Nick Desaulniers > Reviewed-by: Nick Desaulniers > Tested-by: Nick Desaulniers > Reported-by: kbuild test robot > Signed-off-by: Ilie Halip > --- > > Changed in v2: > - added a mention that this is a clang issue across all versions > - added Nick's Reviewed-by, Tested-by > - added Reported-by Thanks. Queued. -- Josh